Lightly crosslinked resins swell greatly when contacted with liquids which solvate the polymer chains For example polystyrene beads cross-linked with 1% DVB swell from 1.7 mL/g to over 6.5 mL/g when contacted with swelling solvents. This swelling makes the inside of the polymer bead more accessible and is often advantageous for washing the resin or performing chemistry on functional groups affixed to the resin. When the washings or chemistry has been completed one is often required to dry the resin. If resin is dried directly from the swollen state the resultant dry product often forms clumps or cluster of beads rather than the desirable free flowing material.
On a commercial or small scale when one dries directly lightly crosslinked resins, by way of example, 1% cross linked, styrene DVB resins (i.e. Merifield resins, CTC resins, unfunctionalized polystyrene, Wang resins, and resins useful for solid phase synthesis) after (1) being in any swelling solvent, e.g. after washing, clumps of beads form and the product becomes non-free flowing. As a result of this subsequent steps are made more difficult, and product performance is degraded. As a result of the clumping phenomenon, during subsequent processing beads on the outside of the clump become over functionalized while beads in the interior of the clump are underfunctionalized. For example, when CTC resins are made, when the resin is charged to a reactive acylating mixture, a mixture of undesirable products is obtained, i.e. dark beads are formed. These dark beads are over functionalized. When one builds a peptide one wants a uniform distribution of functional groups from bead to bead so that the growing peptide chains are not sterically constrained.
Some conventional solid phase synthesis products have the problem of simultaneous overfunctionalization and undefunctionalization as seen by microscopic analysis. There are beads that are inert and beads that are discolored indicating overfuntionalization.
There exists a need in the art to create a uniform distribution of beads with uniform bead to bead performance characteristics.
Another problem with the clumping phenomenon is that the conventional products clog feed tubes, funnels and other manufacturing components. This means that entire systems need to be shut down and cleanend or designed with larger components. There is a need in the art to create free flowing resins that do not clog manufacturing components.
In combinatorial chemistry, it is necessary to have uniform beads since any disparity in uniformity leads to unreliable results. Very small amounts of beads are placed into wells, and when one has over-functionalized or under-functionalized beads the results of the combinatorial study are not reliable.
Normally resins are shipped in bulk containers to end users. If the resins are not free flowing transfer of the bulk resin into manufacturing equipment is made difficult. There exists a need in the industry for free flowing resins that can be used in peptide synthesis and combinatorial synthesis. By way of further example, free flowing products are desirable when charging bulk resin from a bulk container for use in high throughput charging devices, e.g. those that spread materials through small apertures onto plates.
Conventionally, one dries a resin in a swollen state. One problem in following this procedure is that a large drier volume is necessary to dry the swollen resin. A second problem is that once the swollen resin is placed in the drier a much larger amount of solvent must be removed from the swollen resin resulting in longer drying times, and higher energy consumption. After all of these difficulties a lower quality, clumped resin is producted. There exists a need to solve these problems in the art.
Another difficulty is in transferring bulk resin to smaller retail packaging for laboratory uses. If the resin tends to clump, transferring and providing the desired weight accuracy is made more difficult. The resins sold are expensive to manufacture and thus have high selling prices. As such, it is necessary to accurately weigh and package amounts of resin so that the customer is provided the exact amount purchased. There exists a need in the art to provide a resin that is readily transferable from bulk containers into small, laboratory scale packages.
The art has attempted to create free flowing conditions by coating the beads with materials which prevent agglomeration. This method employs materials such as glycerol monostearate and glycerol disterate which persist on the bead after drying. See, DE 2932321. Similar methods,as disclosed in JP 62011740 A2, involve the use of nonionic surfactants such as polyoxyethylenenonylphenyl ether. These patents do not teach or fairly suggest swelling or washing and rely on residues being retained on the beads for their efficacy.
Washing the resins with swelling solvents is known to those skilled in the art. Cameron et. Al (J. Comb. Chem. 2002, 4, 199-203) relates to the use of methanol as a final wash solvent. The resin in this disclosure is a polar quaternary amine which is solvated and swollen by methanol. A similar example can be found in U.S. Pat. No. 6,147,159 (“'159 Patent”) which gives a single example of a resin with methanol as its final wash. However, the resin in the '159 Patent has polyethylene glycol chains which will cause this resin to swell in methanol. Sunil et Al. (J. Comb. Chem, 2001, 3, 9-15) discloses washing with swelling solvents then with ethanol but this procedure was performed on a DVB/Styrene/vinylbenzyl chloride resin with a yield of 42% to less than 80%. The Sunil resin is not the same resin that is the subject of the present invention. Wang (J. Amer. Chem. Soc., 1973, 95, 1328-1333) discloses the washing of a functionalized 1% cross-linked resin with swelling solvents.
There also exists a significant need in the art for methods of manufacturing peptides at commercial scale using solid phase synthesis substrates made using the present invention. While various techniques are known to work at lab scale, these techniques have been found not to scale to industrial equipment well.